Existing cannula devices for providing a portal for arthroscopic and/or laparoscopic surgery are capable of expansion in order to maintain the portal within the tissue into which it has been inserted.
One approach is to include one or more inflatable balloons that are adhesively attached to another instrument. Another approach is a laparoscopic cannula having a distal end that is similar to a “molly bolt,” and is made up of slats. Tissue may be trapped within the openings of the slats during retraction of the device since the distal end portion is discontinuous. The expandable portion of the device is attached to, or is part of, a single outer cannula. Yet another approach is a laparoscopic cannula having an outer disposable part and an inner reusable part that is made of metal. A balloon is provided that is inflated and deflated via a syringe and a stop-cock. Still another approach is an arthroscopic retractor that uses the relative movement of concentric tubes to deploy and retract an expandable distal portion. The expandable portion of the retractor is made of slats or arms, and may be accompanied by an inflatable bladder/balloon. The inflatable bladder/balloon is made of a softer material and requires inflation and deflation through a separate port.
Accordingly, it would be desirable to provide a cannula that does not require external inflation or deflation, and that does not trap tissue upon retraction of the cannula.